1. Field of the Invention
The present invention relates generally to medical devices used to remove occlusions within the vascular system, and more particularly, relates to medical devices used to remove occlusions within the vascular system using mechanical motion.
2. Description of the Prior Art
Devices for treating occlusions of the vascular system of a patient are commonly used in the art. The most popular type of such device is the balloon angioplasty catheter. It is a catheter which is inserted into the vascular system and advanced to the site of the occlusion. A balloon structure, located at the distal tip of the catheter, is inflated to enlarge the lumen at the site of the constriction.
Atherectomy devices are also catheters which are advanced within the vascular system to the site of an occlusion. However, the atherectomy device uses mechanical motion to remove the occlusion, thereby tending to prevent restenosis. U.S. Pat. No. 4,650,466 issued to Luther teaches an atherectomy device having a balloon with a rough outer surface. The balloon is inflated at the site of the occlusion, and rotated to abrade the occluding material.
U.S. Pat. No. 4,765,332 issued to Fischell, et al. discloses an atherectomy device which has a pair of knife blades. These blades are advanced beyond the occlusion and then drawn back to cut away the occluding material. An atherectomy device having a spinning head is shown in U.S. Pat. No. 4,664,112 issued to Kensey, et al.
In the use of each of these and other prior art devices, safety is a major concern. The cutting or abrading surface must not accidentally contact the wall of the vessel for fear of damaging the endothelialized tissue. Furthermore, great care must be exercised to prevent free particles of the occluding material from being conveyed by the blood stream and occluding a vessel in another portion of the vascular system.